Cross-layer Architecture of a Distributed OS for Ad Hoc Networks

Despite the advances in wireless, energy-constrained ad hoc networks, there are still many challenges due to the limited capabilities of the current hardware. Therefore, our aim is to develop a lightweight, yet powerful operating system (OS) for such networks. We reject the brute force method of provisioning all necessary OS services at each node of the system. Instead, in our approach, services provided by the OS organise autonomously to achieve an efficient distribution over the network. In order to enable the use of our OS in energy- and hardware-constrained networks, we argue that it is necessary that all layers of the system are designed to cooperate within a cross-layer approach. At the link layer, our contribution includes an emergent topology control protocol taking into account node and network properties enabling the division of roles between nodes. Further, we employ a combined link metric based on signal strength, success rate, and history to enable a more realistic link quality assessment and pheromone adjustments in routing. At the network layer, to avoid costly reorganisation after role changes incurred by topology control, we use a fuzzy distinction between nodes with different roles by adding a role-based component to the probabilistic next-hop selection function of ant colony routing. At the highest level of our approach, we propose a short- and a long-range migration method for OS service states, based solely on local information and autonomous decisions, to improve the overall quality of service, fairness, balance, predictability, and reduce communication overhead. In ns-2 simulations, we demonstrate improvements of quality of service of 80 % and load balancing of 200 to 400 %